Recently, a robot system has been required to perform an operation on a wide variety of complicated work pieces. Particularly, a robot system needs to be used in diversified small-quantity production. Further, in a robot system, the number of facilities including robots, and the installation area need to be suppressed. For this purpose, the following robot system is introduced. In this robot system, a jig peculiar to each work piece is not used, and a robot for holding a working tool and a robot for holding a work piece are operated in cooperation with each other (hereinafter referred to as a cooperative operation).
FIG. 9 is a diagram showing an example of a conventional robot system using two robots. In FIG. 9, robot D is a master robot that holds working tool 31, and robot E is a slave robot that holds handling device 34. Robot D performs a cooperative operation with robot E on work piece W held by handling device 34 of robot E. Hereinafter, the robot that holds a working tool is referred to as a “working robot”, and the robot that holds a handling device is referred to as a “handling robot”. The robot that gives operation instructions to a slave robot is referred to as a “master robot” and the robot that operates in accordance with the instructions of the master robot is referred to as a “slave robot”.
Cooperative operation of robot D, i.e. a working robot, and robot E, i.e. a handling robot, requires transformation matrix TDE that represents the positional relation between robot coordinate system Σd of robot D and robot coordinate system Σe of robot E. Each of robot D and robot E has a tool center point (hereinafter, a TCP), which is a control point. Conventionally, transformation matrix TDE is calculated by matching the TCP of robot D with the TCP of robot E at three points that are not on one straight line. This operation is referred to as “TCP matching”. The work piece held by robot E is represented by robot coordinate system Σe of robot E. Thus, in cooperative operation, transformation matrix TDE allows robot D to operate with a locus and a velocity represented by work coordinate system Σw in which the TCP of robot E is the origin of the coordinate.
In order to add working robot F to this robot system and to increase operating efficiency, it is required to generate transformation matrix TDF between added working robot F and existing robot D and transformation matrix TEF between added working robot F and existing robot E, and to store the related transformation matrices in the controllers of the respective robots.
The following method is known as one of the methods for addressing this problem. One master robot performs TCP matching with each of a plurality of slave robots, generates transformation matrices equal in number to the slave robots, and stores the transformation matrices in the controller of the master robot. At this time, TCP matching between the slave robots is unnecessary. In automatic operation, the master robot transmits position data on the teaching point and the interpolation point of the master robot to the plurality of slave robots. Based on the position data on the teaching point and the interpolation point that has been transmitted from the master robot, each of the slave robots corrects the teaching point or the interpolation point in the program of the slave robot. Thus, three or more robots can perform a cooperative operation (see Patent Literature 1, for example).